Flow cytometry is an important tool in quantifying and phenotyping the cells that define pathways relevant to diabetes. Previously limited to the analysis of circulating immune cells, advances in cell extraction from tissues has allowed flow cytometry to expand its capabilities to the study of developmental, metabolic and signaling programs in a wide-variety of cell types. The Cytometry & Cell Sorting Core (CCSC) has established itself as a vital and growing component of the Columbia University Diabetes Research Center (DRC), as it addressed the research needs of a growing number of DRC investigators who study immunological, developmental, and metabolic aspects of diabetes. Created in 2010 in partnership with the Columbia Center for Translational Immunology (CCTI) and the Department of Medicine (DOM) with a substantial University investment as well as NIH support, in the past 5 years CCSC has assisted 22 DRC users currently funded by 55 NIH grants, including 30 NIDDK grants. The data generated with the CCSC contributed to 63 publications and 17 new grants. The implementation of CCSC has been essential to support many aspects of diabetes research at Columbia. Since its establishment, the demand for CCSC services has steadily increased, from 60 hours per week with two analyzers to over 130 hours per week with three analyzers, and from 25 hours per week with one sorter to over 60 hours per week with two sorters. We expect usage to continue to grow as new recruits join the DRC, and established investigators take advantage of resources and technologies offered by the Core. Overall, CCSC will assist investigators with the following two aims: Aim 1 ? To quantify and phenotypically characterize cell populations that contribute to the metabolic, immunologic and developmental programs of diabetes and its complications. CCSC leverages advanced technologies in fluorescent imaging at the single cell resolution to support the analysis of many different cell types in both human and animal tissues, as well as humanized mouse models of Type 1 diabetes. Aim 2 ? To purify populations of cells of relevance to diabetes and its complications. Using fluorescence-activated cell sorting, CCSC supports DRC investigators to purify individual populations of cells for in vitro culture, in vivo implantation or molecular characterization including genetic and transcriptional profiling, protein purification and signaling studies, and for functional analysis including T cell activation, proliferation and migration studies. To achieve these aims, the CCSC has established standard operating procedures to: (i) Assure quality control and reproducibility; (ii) Prioritize investigator use; (iii) Monitor Core use; and (iv) Adapt to new technologies and to the needs of the Columbia Research Base.